Apparatus for thermal drilling



Sept. 14, 1965 F. G. FERRABEE 3,205,953

APPARATUS FOR THERMAL DRILLING 4 Sheets-Sheet 1 Filed Aug. 12, 1965 FROMFUEL FROM OXYGEN PUMP SUPPLY I30 INVENTOR. FRANGS 61 FERRABEE BY l I AATTORNEY p 14, 1955 F. G. FERRABEE 3,205,953

APPARATUS FOR THERMAL DRILLING Filed Aug. 12, 1965 4 Sheets-Sheet 2 I meINVENTOR. F A ERRABEE F/G. 2 Z 6 ATTORNEY Se t. 14, 1965 F. e. FERRABEEAPPARATUS FOR THERMAL DRILLING 4 Sheets-Sheet 5 Filed Aug. 12, 1963 FROMOXYGEN SUPPLY FROM FUEL PUMP INVENTOR.

: FRANCIS G. FERRABEE ATTORNEY FIG. 3

Se t. 14, 1965 F. c. FERRABEE 3,205,953

APPARATUS FOR THERMAL DRILLING Filed Aug. 12, 1965 4 Sheets-Sheet 4 FIG.4

ATTORNEY United States Patent C) 3,205,953 APPARATUS FOR THERMALDRILLING Francis G. Ferrahee, St. Bruno, Quebec, Qanada, assignor to(Ianadian lngersoll-Rand Company, Ltd, Montreal, Quebec, Canada, acorporation of Canada Filed Aug. 12, 1963, Ser. No. 301,256 11 Ciaims.(Ci. 17514) The present invention relates to rock drills and moreparticularly to an improved rock drill and to an improved method ofbreaking rocks.

In the art of mining, one of the problems encountered has always beenthe breaking of rocks. Currently, and for some seventy years or more,the best method of breaking rock comprised drilling a series of holes inthe rocks and loading the drilled holes with explosive, prior toshooting or exploding the series of holes.

Some holes, for blasting, are made with conventional rotary drills,which cuts a core of the material, and some by conventional percussiondrills, which reduces the rocks, in the area being drilled, to linecuttings which are blown or washed out of the drilled holes as drillingprogresses. These techniques are in general use.

Lately, attempts have been made to employ heat to melt the rocks, in thearea where the hole is Wanted, and flow the molten material back to thestarting point of the hole. This technique is partially successful.

Attempts have been made to combine rotary and percussion drilling inorder to speed up the process of rotary drilling and to increase thebore of the holes drilled by percussion. Some success has been achievedwith this combination.

U.S. Patent No. 2,628,817 issued to R. O. Wyland, J r. on February 17,1953 recites a method for piercing a hole by use of a burner nozzle.

U.S. Patent No. Re. 22,964, issued to C. I. Burch on January 20, 1948recites a method for piercing holes by melting rock formations under theaction of intense localized heat.

The methods of thermal piercing recited in the U.S. patents enumeratedabove have not been successful commercially for piercing blast holes ofsutlicient depth and smoothness to meet the requirements of mines andquarnes.

Other methods of piercing holes in rock formations such as the use ofpneumaticdrills, saws, or chisels, are often aided by explosives, suchas dynamite. Such mechanical operations are slow and, in the case ofpenumatic drilling for blasting holes in particular, require aninvestment in a large number of drill bits requiring frequentresharpening or replacement. Moreover, the greater the hardness andabrasiveness of the material to be worked, the slower is the rate ofmechanical working and the greater the cost.

It is the general object of the present invention to avoid and overcomethe foregoing and other difiiculties of and objections to the prior artpractices by the provision of a rock drill that will provide holes inrock formations easily and quickly.

Another object of the present invention is to provide a rock drillutilizing heat applied over a rock formation surface to allow easyspalling or shattering of the preheated rock formation by the laterapplication of fairly light percussion blows to the rock formation.

Still another object of the present invention is to provide a faster andmore economic method of drilling holes in rock formations.

The aforesaid objects of the present invention, and other objects whichwill become apparent as the description proceeds, are achieved byproviding an improved rock drill, for providing holes in rockformations, the

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messes Patented Sept. 14, 1965 rock drill having a driven drillingmember and heating means operatively associated with the drilling memberfor preheating rocks thus facilitating the drilling of such rocks. Thedriven member can be rotary driven, reciprocatory driven, or both. Inaddition impact means is disposed in the casing and is slidablyassociated with the first rotation transmitting means for deliveringpercussive blows to the tool holding means. The objects of the presentinvention are further achieved by providing a method for piercing holesin rock formations comprising the steps of heating the rock formations,drilling the rock formations with a drill bit and delivering percussiveblows to the drill bit.

For a better understanding of the present invention reference should behad to the accompanying drawings, wherein like numerals of referenceindicate similar parts throughout the several views and wherein:

FIGURE 1 is a longitudinal sectional view of the rock drill,illustrating the position of the piston in its forwardmost position;

FIGURE 1A is a continuation of the longitudinal sectional view of therock drill continued from line 1A lA of FIGURE 1 in the direction of thearrows;

FIGURE 2 is an enlarged sectional view of the drill bit of FIGURE 1Ashowing in detail the internal combustion chamber in the drill bit;

FIGURE 3 is a detailed sectional view of the upper portion of FIGURE 1;

FIGURE 4 is a sectional view along the line 44 of FIGURE 1 in thedirection of the arrows;

FIGURE 5 is a sectional view along the line 55 of FIGURE 1 in thedirection of the arrows, and showing a gear assembly;

FIGURE 6 is a sectional view along the line 6-6 of FIGURE 1, in thedirection of the arrows, and showing kicker ports;

FIGURE 7 is a fragmentary longitudinal view of a portion of FIGURE 1illustrating the position of the piston in the rearrnost position;

FIGURE 8 is a fragmentary sectional view partially in longitudinalsection of the left side of FIGURE 1 showing a spool type valve in itsrearnost position:

FIGURE 9 is a sectional view of a drill bit illustrating anotheralternative embodiment of the invention;

Although the principles of the present invention are broadly applicableto all drilling apparatus and rock drills of the rotary and percussivetype, the present invention is particularly adapted for use inconjunction with rock drills of the centrally driven independentrotation type, and hence it has been so illustrated and will be sodescribed.

Referring to FIGURES 1 and 1A a conventional rock drill 22 of thecentrally driven independent rotation type, as disclosed in U.S. patentapplication Serial No. 197,655, filed on May 25, 1962, by Paul A.Lincoln, has a casing 20. A first rotation transmitting means, such as ahollow torque. shaft 24, is disposed axially in the drill casing 20 andextends from the back end 26 of the rock drill 22 to the tool or frontend 28 of rock drill 22. The front portion of the torque shaft 24 issplined at 30 (FIG- URE 1A) to engage a splined counterbored portion 32in the rear end of a drilling member, such as a tool holding means (i.e.a drill steel 34 disposed on the drill casing 20 in the tool end 28) anda drill bit 152. Such spline connection 30 is utilized for transmittingrotation to the drill steel 34 by rotary drive means, such as an airmotor 36 (FIGURE 1).

Drive means The rotary air motor 36, as best shown in FIGURES 1 and 4 isdisposed in the back end or head 26 of the rock drill 22 and is providedwith a rotor shaft 38 which is drivingly connected to the torque shaft24 and in turn is supported for rotation in bearings 48 and 42 (FIG. 1).The bearings 40 and 42 are disposed in supporting walls 44 and 46 of theback end 26 of the rock drill 22. Since the air motor 36 is locatedadjacent to the torque shaft 24 and also has a far greater rotation inr.p.m. than the desired rotational speed of the drill steel 34, a secondrotation transmitting means, such as a gear assembly (comprising aneccentric 48, internal oscillating gear 50, and driven gear 52 (FIGS. 1and is provided to accomplish the dual purpose of transmitting rotationfrom the air motor 36 to the torque shaft 24 (to attain central rotationdrive) and of reducing the rotation speed required to properly drive thedrill steel 34.

To provide the central rotation drive, at reduced speed, of the torqueshaft 24, the air motor 36 rotatably drives the internal oscillatinggear 58 through the eccentric 48 on the rotor shaft 38; the internaloscillating gear 58 in turn driving the driven gear 52. The driven gear52 in turn transmits rotation to the torque shaft 24 through spline 56.Therefore, it can be seen that axial rotation of the drill steel 34 isachieved by the above described drive means.

Inasmuch as the rotational speed of the air motor 36 is far greater thanthe desired rotational speed of the drill steel 34, the r.p.m. generatedby the air motor 36 must be reduced before it is delivered to the drillsteel 34. The required speed reduction is accomplished by providing theeccentric 48 at the forward end 58 of rotor shaft 38 (FIG. 1) disposedwithin an axial bore in the internal gear 50. The external gear 52surrounds gear 58 and is spline connected at 56 to the torque shaft 24to accomplish the transmittal of rotation from air motor 36 to thetorque shaft 24. A pin 60 (FIGS. 1 and 5), having one end retained incasing wall 46 (FIG. 1), extends into a hole 62 in internal gear 58(FIG. 1). Pin 60 serves to prevent rotation of internal gear 50 so that,as eccentric 48 rotates, internal gear 50 is oscillated into engagementwith the teeth of external gear 52. Sufiicient clearance is allowed pin68 in wall 46 to permit the internal gear 50 to follow the eccentric 48.

For each revolution of eccentric 48, the external gear 52 is rotated twoteeth. It can be seen that if the internal gear 50 and the external gear52 are provided with 34 and 36 teeth respectively, a speed reduction of18 to 1 is achieved so that with a motor speed of 3,200 r.p.m., thedrill steel 34 will be rotated at 178 r.p.m.

The speed of rotation of the air motor 36 may be varied by means of athrottle valve 64 (FIG. 4) disposed in a fluid supply passage or inlet65 to the air motor 36. Therefore, as above indicated, the rotation ofthe external gear 52 causes rotation of torque shaft 24 by reason of thespline connection at 56. Rotation of the torque shaft 24 is transmittedto the drill steel 34 through the spline connection at 38 thusaccomplishing the desired central drive of the torque shaft 24.

Impact means In order to deliver impact blows to the drill steel 34 anddrill bit 152 simultaneously but independently from the rotation of thetorque shaft 24, impact means, such as an axial motor having a hammerpiston 66, is provided.

The hammer piston '66 (FIGURE 1) is provided with an axial bore 68through which torque shaft 24 extends, and is reciprocably mounted in anaxial motor cylinder 70 which is closed at one end by a conical wall'72. This wall 72 and a rearwardly spaced wall 74 define a plenumchamber 76 which receives fluid, such as air, under pressure from asupply port 78. Toprevent fluid leakage from plenum chamber 76,.thespace between walls 72 and 74 are made fluid tight by seals 80. As shownin FIGURE 1, a spool type valve 82 is disposed in plenum chamber 76 tocontrol flow of pressure fluid to cylinder 70 through suitable portingto thereby effect reciprocation of hammer piston 66.

The reciprocating movement of the hammer piston 66 is accomplished byair being admitted through passage 84 and port 86 to the front supplycavity 88 of the hammer piston 66 (FIGURE 1) to move or drive the hammerpiston 66 rearwardly from the striking position,

as shown in FIGURE 1, to the retracted position until its front edge 90uncovers the front kicker port 92, as shown in FIGURE 7. The uncoveringof the port 92 permits pressurized air to pass therethrough and move ordrive valve 82 rearwardly causing a valve edge 94 thereof to move fromthe position shown in FIGURE 1 to the position shown in FIGURE 8, biasedtoward the back end 26 of the rock drill 22. As the valve 82 movestoward the back end 26 of the rock drill 22, it closes the passage 84 toshut off the air supply to the front supply cavity 88 of the hammerpiston 66. At the same instant as the spool type valve 82 is moving toclose passage 84 it exposes a rear supply port 96 (FIG. 8) which emitsair through a rear supply cavity 98 to slow down and stop the hammerpiston 66 in the retracted position of FIGURE 7.

Pressure then rapidly builds up in the rear supply port 96 and begins topush or drive the hammer piston 66 forward from the retracted positionshown in FIGURE 7 to the striking position shown in FIGURE 1, toward thedrill steel 34. As the hammer piston 66 is moving back to the strikingposition shown in FIGURE 1, an exhaust port 180 is uncovered therebyexhausting the front supply cavity 88 to the atmosphere. As the hammerpiston 66 moves forwardly, a back edge 102 thereof uncovers a backkicker port 104, as shown in FIGURE 1, and permits pressurized air toenter a cavity 106a and act against a kicking flange 106 of the valve 82(FIG. 1) thereby causing valve edge 94 to move forwardly toward thedrill steel 34 and permit air to enter the front supply cavity 88. Theback edge 102 of the hammer piston 66 now moves forward thus opening therear supply cavity 98 to exhaust the air from the front supply cavity88.

Thereafter the cycle of the hammer piston 66 is repeated. As the hammerpiston 66 reciprocates, it imparts to the shank piece 108 or back end ofthe drill steel 34 impact energy which is, of course, transmitted to thedrill steel 34. Thus it can be seen how impact energy is supplied to thedrill steel 34.

In order to supply heat to front or bit end 110 of the drill steel 34.and thus .to heat the rock formation 112 being drilled, a heating meanssuch as a burner nozzle assembly 114 is provided.

Heating means The burner nozzle assembly 114 or heating means, shown inFIGURES 1 to 3, is provided with a tube 116 which extends substantiallythe full length of the rock drill 22 from the bit end 118 of the drillsteel 34 to the back end 26. At the bit end 118 of the tube 116, astandard fuel ejector 128 (FIGURE 2) is positioned to receive a fuel,such as kerosene or other hydrocarbon fluids, and to eject the fuel intoan external combustion chamber 122. The fuel is delivered to the fuelejector 120 by a fuel pipe 124 which is flow connected to orcommunicates with .a fitting 126 threaded on the back end 26 of the rockdrill 22. The fitting 126 is adapted to receive the discharge line (notshown) of a fuel pump (not shown) which serves as the fuel supply to theburner nozzle assembly 114, and forms no part of the present invention.The fuel pipe 124 is secured at its lower end within a bore 127 (FIGURE2) in the nozzle end .136 of the burner nozzle assembly 114 throughwhichthe fuel flows to fuel ejector 120 for discharge into the internalcombustion chamber 122.

A combustion supporting medium, such as gaseous oxygen, is supplied tothe internal combustion chamber 122 by an oxygen supply means (notshown), connected to an oxygen fitting 128 which is threaded on the backend 26 of the rock drill 22 (FIGURES 1 and 3). The oxygen flows throughthe oxygen fitting 128 to a longitudinally disposed oxygen pipe .130,secured within the tube 116, which extends downwardly and is connectedat its lower end 138 to a header 134 journalled in the nozzle end .136of the burner nozzle assembly 114, as shown in FIGURE 2. Header 134 hasa bore 132 providing communication for oxygen pipe 130 or a dischargeforoxygen into the internal combustion chamber 122. The lower end .138of the oxygen pipe 130, can be connected in the header 134 by any numberof well known methods, such as the ball joint connection shown in FIG-URE 2 to allow for the rotation of the drill bit 152.

The fuel and oxygen mix in internal combustion chamber 1'22 and uponcombustion therein a hot high viscosity illame leaves the nozzle end 136through outlet 144. The start of combustion in combustion chamber 122,can be accomplished by a number of igniting methods known to thoseskilled in the art as for example a spark gap or carbon are fed byelectrical conductors (not shown) connected to a source of power (notshown). The combustion chamber is lined with a layer .of insulatingmaterial 145 (FIGURE 2) to insulate the drill bit 152 from the heatgenerated in the combustion chamber 122.

Lubricating means In order to provide lubrication to the front end 28 ofthe rock drill 22, an inlet 146 is provided in the back end 26 of therock drill 22 which communicates with the tube 116 and is 'adapoted toreceive .a lubricant supply outlet, such as a flexible hose (not shown)which supplies lubricant, such as water. The lubricant flows through thetube 116, around the pipe 124-, and enters an annular space 148 to coolthe nozzle end 136, and is then discharged from the nozzle end 136,through a plurality of circumferentially arranged radial ports 150(FIGURE 2) located in the drill bit 152 for cooling the drill bit 152and for quenching .and moistening detritus which is separated from therock formations by the flame.

Thus the rock drill 22 drills holes (FIGURE 1A) in rock formations byuse of heat, rotational drilling, and impact blows.

Operation- Although the operation of the apparatus should be apparentfrom the foregoing description, a brief description of such operationwill now be made for purposes of summary and simplification. A fuel anda combustion supporting medium are individually fed by pipes 124 and130, to an internal combustion chamber 122 wherein they are ignited bymeans (not shown) and form a flame which protrudes past the drillingmember or drill bit 152 to heat the rock formations to be drilledthereby. The heating of the rock formations serves to produce internalstresses in the rock formations thus reducing their resistance tomechanical drilling.

The air motor 36 provides torque to rotate the torque shaft 24, at adesired speed, through gears 48, 50 and 52. The torque shaft 24 in turndelivers torque to rotate drill steel 34 and its drill bit 152 to drillthe rock formations.

In addition, operating independently but coaxially with the torque shaft24, the reciprocating percussive member or hammer piston 66 deliversimpact blows to the drill steel 34.

The flame, which may range in intensity from 200 F. on up to 1000 F., ismoved over the surface of a rock formation at a rate of speed designedto produce enough internal stress in the rocks, to allow fairly lightpercussion blows from the hammer piston 66 to cause heavy spalling ofthe rock formations which rock formations when rotationally drilled bythe drill bit 152, are reduced to fine material that are easily removed.Thus holes of any desirable diameter are produced in rock formationseconomically and accurately.

Alternative embodiments Alternatively, as shown in FIGURE 9, heat can beprovided in front of the drill bit .152" by electrical means such as aspark gap 162" or carbon are fed by electrical conductors 164" connectedto a power supply source (not shown).

Further alternatively it will be understood that the heating means shownin FIGURES 1 and 1A can be employed in combination with a conventionalrotary type rock drill to form a rock drill having rotary drilling meansand heating means for drilling rocks.

Still further alternatively the heating means shown in FIGURES 1 and 1Acan be employed in combination with a conventional percussive rock drillto form a rock drill having percussive means and heating means fordrilling rocks.

Still further, alternatively rock formations can be heated by the use ofchemicals which are delivered to rock formations by tube means such asthe tubes 116 and shown in FIGURE 1. There are many such well knownchemicals which when mixed on the rock formations would react to createsuflicient heat to cause easy spalling of the rocks. It is of courseunderstood that the tubes 116 and 130 would be constructed of materialthat could not be harmed by the chemicals.

It will be recognized by those skilled in the art that the objects ofthe present invention have been achieved by providing an improved rockdrill which utilizes the combination of heat, rotary drilling, andpercussion to drill holes in rock formations easily and more efficientlyby introducing a flame or heat source ahead of the drill bit to causesutlicient internal rock pressure for easy spalling of the rockformations.

While in accordance with the patent statutes a preferred embodiment ofthe present invention has been illustrated and described in detail, itis to be particularly understood that the invention is not limitedthereto or thereby.

I claim:

1. A rock drill comprising:

( a) casing means;

( b) impacting and rotational driving motor means disposed in the casingmeans;

(c) a drilling tool supported in the casing means and extendingtherefrom;

(d) the drilling t-ool being operatively connected to the motor means tobe driven thereby and having means outside of the casing means forengaging and mechanically drilling a rock formation; and

(e) means disposed in the mechanical drilling means for heating the rockformation to be drilled for producing internal stresses therein tofacilitate mechanical drilling.

2. A rock drill in accordance with claim 1, and further comprising:

(a) inlet supply means disposed in the drilling tool, communicating withthe heating means and being connected to the casing means to provide aconnection to a supply source.

3. A rock drill in accordance with claim 2, wherein:

(a) the inlet supply means extends through the motor means.

4. A rock drill in accordance wit-h claim 2, and further comprising:

(a) supply means being disposed in the drilling tool for providinglubrication to the mechanical drilling means, extending into the casingmeans and through the motor means, and being connected to the casingmeans to provide a connection to a supply source.

5. A rock drill comprising:

(a) casing means;

(b) impacting and rotational driving motor means disposed in the casingmeans;

(c) a drill steel supported in the casing means and extending therefrom,and being operatively connected to the motor means to be driven thereby;

'(d) a drill bit connected to the drill steel outside the casing meansfor engaging and mechanically drilling a rock formation when the drillsteel is driven; and

(e) a burner nozzle assembly disposed in the bit for providing heat tothe rock formation to be drilled for producing internal stresses thereinto facilitate mechanical drilling.

6. A rock drill in accordance with claim 5, and further comprising:

'(a) electrical spark gap means disposed in the nozzle assembly toprovide a spark when connected to a source of electrical energy forcreating heat in the nozzle assembly to be provided to the rockformation to be drilled.

V 7. A rock drill in accordance with claim and '(a) the casing meanshaving inlet means adapted to receive fuel for combustion in the burnernozzle assembly and an oxidizing agent to support such combustion; and

'(b) a pair of conduits disposed in the drill and extending into thecasing means each communicating with the inlet means at one end and withthe burner nozzle assembly at the other end to provide a flow path forfuel and a flow path for the oxidizing agent.

8. A rock drill in accordance with claim 7, wherein:

(a) the pair of conduits extend through the motor means.

9. A rock drill in accordance with claim 7, wherein:

(a) one of the pair of conduits is disposed within the other.

10. A rock drill in accordance with claim 7, and having lubricatingmeans comprising:

(a) inlet means in the casing means adapted to receive lubricant;

'(b) a conduit disposed in the drill steel which extends into the casingmeans and communicates with the inlet means to receive lubricanttherefrom;

(c) an annular chamber defined between the bit and the burner nozzleassembly; and

(d) the annular chamber communicating at one end with the lubricantconduit and having discharge ports at its other end extending throughthe bit. 11. A rock drill in accordance with claim 10, and:

' (a) the pair of conduits and the lubricant conduit being disposed onewithin the other and extending through the motor means.

References Cited by the Examiner UNITED STATES PATENTS 595,969 12/97Plumb 74-830 1,284,398 11/18 McKinlay --11 XR 2,111,872 3/38 Rea 17511XR 2,675,994 4/54 Smith et al 17515 XR 2,810,549 10/57 Morrison 175--296XR 2,882,016 4/59 Aitchison et a1 175-14 2,935,303 5/60 Royer et al.175-14 3,004,137 10/61 Karlovitz 175-16 XR 3,045,766 7/62 Fleming 175143,093,197 6/63 Freeman 17514 3,103,251 9/63 Browning 175-14 CHARLES E.OCONNELL, Primary Examiner.

1. A ROCK DRILL COMPRISING: (A) CASING MEANS; (B) IMPACTING ANDROTATIONAL DRIVING MOTOR MEANS DISPOSED IN THE CASING MEANS; (C) ADRILLING TOOL SUPPORTED IN THE CASING MEANS AND EXTENDING THEREFROM; (D)THE DRILLING TOOL BEING OPERATIVELY CONNECTED TO THE MOTOR MEANS TO BEDRIVEN THEREBY AND HAVING MEANS OUTSIDE OF THE CASING MEANS FOR ENGAGINGAND MECHANICALLY DRILLING A ROCK FORMATION; AND (E) MEANS DISPODED INTHE MECHANICAL DRILLING MEANS FOR HEATING THE ROCK FORMATION TO BEDRILLED FOR PRODUCING INTERNAL STRESSES THEREIN TO FACILITATE MECHANICALDRILLING.